Skip to Content

Haldol Decanoate Side Effects

Generic Name: haloperidol

Medically reviewed by Last updated on Oct 21, 2020.

Note: This document contains side effect information about haloperidol. Some of the dosage forms listed on this page may not apply to the brand name Haldol Decanoate.

For the Consumer

Applies to haloperidol: oral solution, oral tablet

Other dosage forms:


Oral route (Tablet)

Elderly patients with dementia-related psychosis treated with atypical antipsychotic drugs are at an increased risk of death compared to placebo. Although the causes of death in clinical trials were varied, most of the deaths appeared to be either cardiovascular (eg, heart failure, sudden death) or infectious (eg, pneumonia) in nature. Observational studies suggest that antipsychotic drugs may increase mortality. It is unclear from these studies to what extent the mortality findings may be attributed to the antipsychotic drug as opposed to patient characteristics. Haloperidol is not approved for the treatment of patients with dementia-related psychosis.

Side effects requiring immediate medical attention

Along with its needed effects, haloperidol (the active ingredient contained in Haldol Decanoate) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking haloperidol:

More common

  • Difficulty with speaking or swallowing
  • inability to move the eyes
  • loss of balance control
  • mask-like face
  • muscle spasms, especially of the neck and back
  • restlessness or need to keep moving (severe)
  • shuffling walk
  • stiffness of the arms and legs
  • trembling and shaking of the fingers and hands
  • twisting movements of the body
  • weakness of the arms and legs

Less common

  • Decreased thirst
  • difficulty in urination
  • dizziness, lightheadedness, or fainting
  • hallucinations (seeing or hearing things that are not there)
  • lip smacking or puckering
  • puffing of the cheeks
  • rapid or worm-like movements of the tongue
  • skin rash
  • uncontrolled chewing movements
  • uncontrolled movements of the arms and legs


  • Confusion
  • convulsions (seizures)
  • difficult or fast breathing
  • fast heartbeat or irregular pulse
  • fever (high)
  • hot, dry skin, or lack of sweating
  • increased blinking or spasms of the eyelid
  • increased sweating
  • loss of bladder control
  • muscle stiffness (severe)
  • muscle weakness
  • sore throat and fever
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unusual bleeding or bruising
  • unusual facial expressions or body positions
  • unusual tiredness or weakness
  • unusually pale skin
  • yellow eyes or skin

Incidence not known

  • Continuing nausea or vomiting
  • increase in the frequency of seizures
  • loss of appetite
  • swelling of the face
  • tiredness and weakness

Get emergency help immediately if any of the following symptoms of overdose occur while taking haloperidol:

Symptoms of overdose

  • Difficulty with breathing (severe)
  • dizziness (severe)
  • drowsiness (severe)
  • muscle trembling, jerking, stiffness, or uncontrolled movements (severe)
  • unusual tiredness or weakness (severe)

Side effects not requiring immediate medical attention

Some side effects of haloperidol may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Blurred vision
  • changes in menstrual period
  • constipation
  • dryness of the mouth
  • swelling or pain in the breasts (in females)
  • unusual secretion of milk
  • weight gain

Less common

  • Decreased sexual ability
  • drowsiness
  • increased sensitivity of the skin to sun (skin rash, itching, redness or other discoloration of skin, or severe sunburn)
  • nausea or vomiting

For Healthcare Professionals

Applies to haloperidol: compounding powder, injectable solution, intramuscular solution, oral concentrate, oral tablet


The most common side effects include extrapyramidal disorder, insomnia, and agitation.[Ref]

Nervous system

Acute dystonia usually occurred early in treatment.

Sedation may occur more frequently in elderly patients.

Akathisia usually occurred within 6 hours of administration and may be indistinguishable from psychotic agitation.[Ref]

Very common (10% or more): Extrapyramidal disorder (up to 34%), hyperkinesia (up to 13%), headache (up to 12%)

Common (1% to 10%): Tardive dyskinesia, dystonia, dyskinesia, akathisia, bradykinesia, hypertonia, somnolence, masked facies, tremor, dizziness, parkinsonism/parkinsonian effects

Uncommon (0.1% to 1%): Convulsion, akinesia, cogwheel rigidity, sedation, involuntary muscle contractions, gait disturbance, persistent tardive dyskinesia

Rare (0.01% to 0.1%): Motor dysfunction, neuroleptic malignant syndrome, nystagmus

Frequency not reported: Drowsiness, epileptic/grand mal seizure, vertigo, lethargy

Postmarketing reports: Opisthotonos[Ref]


Very common (10% or more): Insomnia (up to 19%), agitation (up to 15%)

Common (1% to 10%): Depression, psychotic disorder

Uncommon (0.1% to 1%): Confusion, increased/decreased libido, restlessness, hallucinations

Frequency not reported: Apparent exacerbation of psychotic symptoms, anxiety, euphoria, agitation, apprehension, toxic psychosis, catatonic-like behavioral states[Ref]


Common (1% to 10%): Constipation, dry mouth, salivary hypersecretion/hypersalivation, nausea, vomiting

Frequency not reported: Dyspepsia, diarrhea, heartburn, excessive salivation[Ref]


Common (1% to 10%): Urinary retention, erectile dysfunction, sexual dysfunction

Uncommon (0.1% to 1%): Amenorrhea, dysmenorrhea, galactorrhea, breast discomfort/pain

Rare (0.01% to 0.1%): Menorrhagia, menstrual disorder

Frequency not reported: Priapism, oligomenorrhea, mastalgia, breast engorgement, lactation[Ref]


Common (1% to 10%): Orthostatic hypotension, hypotension

Uncommon (0.1% to 1%): Tachycardia, edema

Rare (0.01% to 0.1%): QT prolongation (on ECG)

Frequency not reported: Ventricular fibrillation, Torsade de pointes/polymorphous configuration of Torsade de pointes, ventricular tachycardia, extrasystoles, peripheral edema, venous thromboembolism, deep vein thrombosis, unusual bleeding, heat stroke

Postmarketing reports: Ventricular arrhythmia, cardiac arrest, hypertension[Ref]

QT prolongation, Torsade de pointes, ventricular arrhythmias/fibrillation/tachycardia and cardiac arrest occurred more frequently at high doses and/or in patients at risk for cardiovascular side effects.

Tachycardia and hypotension may occur more frequently in elderly patients. Hypotension occurred as a dose-related event.

Heat stroke included hot, dry skin, the inability to sweat, muscle weakness, and/or confusion.[Ref]


Common (1% to 10%): Weight increased/decreased

Frequency not reported: Hypoglycemia, hyperglycemia, loss of appetite, anorexia, hyponatremia

Postmarketing reports: Hyperammonemia[Ref]

Hyperammonemia occurred in a pediatric patient with citrullinemia (inherited disorder of ammonia excretion).[Ref]


Common (1% to 10%): Oculogyric crisis, visual disturbance

Uncommon (0.1% to 1%): Blurred vision

Frequency not reported: Cataracts, retinopathy[Ref]


Common (1% to 10%): Rash

Uncommon (0.1% to 1%): Photosensitivity reaction, urticaria, pruritus, hyperhidrosis

Frequency not reported: Exfoliative dermatitis, leukocytoclastic vasculitis, Toxic epidermal necrolysis, Stevens-Johnson syndrome, erythema multiforme, maculopapular/acneiform skin reactions, alopecia[Ref]


Common (1% to 10%): Muscle rigidity

Uncommon (0.1% to 1%): Torticollis, muscle spasms, musculoskeletal stiffness

Rare (0.01% to 0.1%): Trismus, muscle twitching

Postmarketing reports: Rhabdomyolysis[Ref]


Common (1% to 10%): Hyperthermia

Uncommon (0.1% to 1%): Unusual tiredness/weakness

Frequency not reported: Neonatal drug withdrawal syndrome, sudden/unexpected death, face edema, hypothermia[Ref]


Common (1% to 10%): Abnormal liver function test

Uncommon (0.1% to 1%): Hepatitis, jaundice

Frequency not reported: Acute hepatic failure, cholestasis, impaired liver function[Ref]


Common (1% to 10%): Injection site reaction

Frequency not reported: Injection site abscesses, localized erythema/swelling/tender lumps[Ref]


Uncommon (0.1% to 1%): Dyspnea

Rare (0.01% to 0.1%): Bronchospasm

Frequency not reported: Laryngeal edema, laryngospasm, pulmonary embolism, increased respiratory rate/depth, sore throat, bronchopneumonia/lethal bronchopneumonia[Ref]


Agranulocytosis included sore throat/fever and unusual bleeding/bruising, and typically occurred with concurrent use of other drugs.

Leukopenia and leukocytosis were usually mild and transient.[Ref]

Uncommon (0.1% to 1%): Leukopenia

Frequency not reported: Agranulocytosis, neutropenia, pancytopenia, thrombocytopenia, unusual bruising, decreased red blood cell counts, anemia, lymphocytosis, monocytosis, lymphomonocytosis[Ref]


Uncommon (0.1% to 1%): Hypersensitivity reactions

Frequency not reported: Anaphylactic reaction[Ref]


Rare (0.01% to 0.1%): Hyperprolactinemia

Frequency not reported: Inappropriate antidiuretic hormone secretion, gynecomastia[Ref]

Inappropriate antidiuretic hormone secretion occurred with hyponatremia[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Haldol (haloperidol)." McNeil Pharmaceutical, Raritan, NJ.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.